"You can't go in the water yet! You just ate! Wait half an hour and sit there quietly, otherwise you'll drown!"

A stern warning from mom about drowning/vomiting/mean cramps was enough to strike fear into the hearts of most children, but there were always those skeptics--the kids who swore that it was a-OK to down a hot dog and jump right back into the swimming pool.

As adults, we tend to think a little more carefully about the warnings our parents issued during our childhood. Will walking outside in the rain when it's chilly really make you get a cold? (No.) Will your face really freeze that way? (Absolutely not.) Can you die from swimming right after eating?!

Photo by Kaitlin Steinberg

Swimming and boozing is probably not a great idea.

Again, the answer is of course not, but the question deserves a few more words than a simple "no." To squash the nasty rumor once and for all, we need to understand why parents tell this strange lie to their kids and the science behind it.

According to the CDC, between 2005 and 2009, the average annual number of unintentional fatal drownings was 3,533. About 1 in 5 of these victims is a child aged 14 or under. Listed as factors that influence drowning risk: Lack of swimming ability, lack of barriers, lack of close supervision, location, failure to wear life jackets, alcohol use and seizure disorders. Swimming too soon after enthusiastically downing too many hot dogs is apparently not a factor.

What's true is that when we digest, increased blood flows to our stomachs in order to absorb nutrients from the food we've just consumed. The theory behind the swimming warning is that this takes blood away from other vital organs, depriving them of oxygen and causing cramps. In reality, we have a lot of blood--plenty, in fact, to service all other organs while we're digesting. Ever see a runner down a protein bar in the midst of a marathon? The runner isn't worried about getting a stomach cramp from the meal, no matter its size. He or she just needs more energy to keep going.

"But wait!" you're thinking. "When I eat a big meal and run right after, I do get a cramp!" First of all, don't do that if it gives you stomach cramps. Second, the cramps aren't caused by the food itself. They're caused by lactic acid buildup in the stomach muscles due to blood being sent away from your stomach and to your skeletal muscles to aid in the whole movement thing. The stomach will cramp like any muscle when deprived of oxygen.

This phenomena varies from person to person. It's entirely likely that your kid could eat a giant burger, go swimming five minutes later and then come crying to you that he feels sick. But in that case, vomiting is a much greater concern than death by tummy ache. From what we and other researchers have been able to find, there is not a single drowning death that can be attributed to swimming too soon after eating.

So how'd the nasty rumor start? One of the earliest references comes from the book Scouting for Boys by Robert Baden-Powell, published in 1908. In it, he writes: "First, there is the danger of cramp. If you bathe within an hour and a half after taking a meal, that is, before your food is digested, you are very likely to get cramp. Cramp doubles you up in extreme pain so that you cannot move your arms or legs -- and down you go. You may drown -- and it will be your own fault." Baden-Powell was the first chief scout of The Boy Scouts Association and a lieutenant-general in the British Army. Unsurprisingly, he had no medical training.

People who grew up in the 1950s and '60s are likely to repeat the myth, as their parents did to them. A theory behind that is that public pools became much more popular than previously during that time period. There weren't as strict safety standards in place as there are today with life guards on watch at all times, and parents wanted a break.

"OK, Timmy," they'd say. "You have to sit here and be very still for 45 minutes or you could die." And then they'd turn back to their magazine and cigarette.

While discussing this old wives' tale in the Houston Press office, a number of parents admitted to telling their children that little white lie for just such a reason. They needed a moment of respite from watching the children with an eagle eye. Worrying can be very tiresome.

So when you're hitting the pool or the bay this summer, know that you don't have to be sidelined for 30 minutes or more after you eat. You might vomit, but you won't die.